Voltage regulation of dynamo-electric alternating-current machinery.



M. SEIDNER.

VOLTAGE REGULATION OF DYNAMO ELECTRIC ALTERNATING CURRENT MACHINERY.

APPLICATION FILED JULY 29, 1910.

980,844. I Patented Jan. 3, 1911.

' Mama gel- (9 1/41: ,W, ki 9wm 7% UNITED STATES PATENT OFFICE.

MICHAEL'SEIDNER, 0F BUDAPEST AUSTRIA-HUN GARY, ASSIGNOR TO AKTIENGESELL-SCHAFT BROWN BOVERI & CIE., 0F BADElll' SWITZERLAND.

VOLTAGE REGULATION OF IQKNAMO-ELECTBIC ALTEBNATING- CURRENT MACHINERY.

Specification of Letters: Patent.

Patented Jan. 3, 1911.

Application filed July 29, 1910. Serial No. 574,585.

To all whom it may concern:

Be it known that I, MICHAEL SEIDNER, a subject of the King of Hungary,and residing at Zsigmondstrasse 5, Budapest 11, Austrla-Hun ary, haveinvented certain new and usefu Improvements in and Relating to theVoltage Regulation of Dynamo-Electric Alternating-Current Machinery, ofwhich the following is a specification.

This invention relates to means for regulating the voltage of dynamoelectric alternating current machinery.

Regulating apparatus for alternating current generators heretoforeproposed including resistances in the exciting circuit which vary theirconductivity considerably .with the temperature, have certaindisadvantages. Many apparatus for instance require or re sult ininvolved connections. For example they require transformers with severalcoil divisions and terminals, which lead to unusual constructions. Inother arrangements the voltage and current components of the currentnecessary for regulation are combined by two ordinary transformers or bya single transformer and two independent magnetic fields. In order toavoid the mutual or relative reaction of the two components to becombined and the penetration of direct current into the alternatingcurrent circuit or vice versa, special-resistances must be em loyed or eulpotential points provided y the aid of resistances. A furtherdisadvantage of this apparatus is that the loss of energy in the ohmicresistances is too great, thus causing the etliciency ofthe currentgenerator to be reduced and rendering the regulating apparatus and theworking more expensive. The rapidity of the regulation with theseapparatus also leaves much to be desired. As either the auxiliary ohmicresistances or the secondary coil itself of the voltage transformer areconnected in parallel with the regulating resistances, the greater. artof the rush of current or decrease of currentmomenta-rily produced bythe current transformer in its secondary winding when a sudden variationof load occurs, flows through the parallel connected resistances or thevoltage coil or istaken therefrom. The iron resistances cannot.

therefore effect the required sudden increase or decrease of thealternating current volt:

in which the regulating resistances are connected together to form anindependent or closed system to which direct or alternating current issupplied, and from which it is conducted away at equipotential points,the

alternating current being taken from a mixed transformer in connectionwith the main current and the potential of the alternatingcurrentgenerator in such a manner that the regulating resistances soadjust themselves under the current fed to them directly or indirectlyfrom this transformer that the voltage of the alternating current:generator is maintained constant with varying load and varying phasedisplacement.

The invention also consists in the improvements in and relating to theregulation of alternating currentdynamo electricmachinery hereinindicated.

F igure 1 is a diagram illustrating one manner of carrying the inventioninto effect. Figs. 2 and 3 are, diagrams hereinafter referred to. I

- In this form a three-phase alternating current generator G feeds'themains 1, 2 and} and is excited from an exciting machine 0, supplying thegenerator field winding a. The field f of the exciter e is connected tothe exciter terminals by way of two points p and q in a resistancesystem denoted generally by h which points represent equipotentialpoints as regards alternating current. The resistance system it is aclosed system and in addition to the two connections already referredto, it has others t and s which are equipotential points as regardsdirect current and are connected to the secondary .Of a transfonner k.This transformer is connected to the generator as to one side, at 4 andas to its other side is connected to one terminal of a transformergenerally referred to as a: and including two coils 1- and Z and a corem. In the resistance system b the alternating current from the secondaryof the transformer k enters at the points a and t, which areequipotentially dlstant from the direct current connections 72- and g,whereby direct current flowing between 77 and g does not overflow intothe alternating current leads. The same is true as to the alternatingcurrent and the direct current leads. The alternating current heats theregulating resistance which acts merely as a resistance element in thedirect current circuit, that is, in the field circuit of the exciter e.If the alternating current traversing the resistance element changes,then the temperature and consequently the resistance of the element Itwill change or.vary correspondingly, and thus effect the current in thefield circuit f, so that the excitation of the alternator will be variedin like manner. The coils r at the end which is not connected with thetransformer is is connected to the alternating current generator, forexample, at 5, so that it is excited according to the potential of thegenerator, and the coil Z is connected between the points 5 and 3 sothat it is excited by the outgoing current of the generator. The numberof the turns of the two coils 1' and Z connected in series is such thatthe greater part of the terminal voltage of G is taken by r so that theprimary coil of receives a certain current through 7'. This currentdepends on the one hand on the no-load current of the mixed transformerT Z and on the other hand on the load current of the generator, as thewinding 1' creates a counter magnetomotive force which is equal butopposite in direction to the magnetomotive force of Z. The two windingsof the mixedtransformer 1' and Z are so connected that with anon-inductive load the component magnetomotive forces of Z and 1'in'close the angle of more than 90, while with increasingphase-displacement of the load this angle increases and the resultantcurrent decreases. This will be seen from Fig. 2 where A. B. is themagnetomotive force of r at no load. C B is the ma etomotive force of Zat cos. =1. Thus t e vector A C represents the resultant magnetomotiveforce. As the number of turns of the transformer 7' Z is constant thisdiagram also indicates the current in r Z. The resultant current A C isconducted to the regulating resistances through the current transformer70. Thus the regulating resistances will be influenced accordingly bythe voltage, current and phase-displacement of the generator.

The apparatus described above operates as follow'sz-When the currentgenerator is running light, the voltae coil 1 receives a current whichcorrespon s to the magnetization of the transformer. This magnetizationcurrent flows through the current transformer is and induces current inthe regulating resistances and is sufliciently hi h'to cause theresistance of the latter to so adjusted under the influence of thetemperature that the amount of direct current necessary for exciting thema ets f of the exciter machine 6 is automatlcallyobtained. The currentcoil Z is without current and thus has no influence whatever onthe-regulation. It'receives at its terminals from the winding 1* a lowinduced voltage, which only influences the terminal voltage of thecurrent generator to an unimportant degree. If load be put on thegenerator the load current flowing through the winding Z affects thewinding 1' in proportion to the increase.-

of the load current and its phase-displacement. The regulatingresistances h thus receive a weaker alternating current, so that theirresistance decreases, the intensity of the direct current, however,increases and the excitation of the current generator is also increased.By suitabl calculating the number of ampere-turns-o Z, anover-compounding may be attained.

It is diflicu t to arrange the apparatus so that the regulatingalternating current varies exactly to the same extent as is required bythe excitation of the exciter machine to obtain a constant voltage ofthe generator. With different loads, therefore, a variation in voltagewill always occur to some extent. To obviate this objection or torestrict it to practically negligible limits, the transformer 1' Z is soarranged that its iron core works at high saturation. This enables theno-load current in the coil r when the terminal voltage'varies, forexample, slightly, to vary to a far greater extent per' cent. On anincrease of the voltage of the generator for example by 3%, the terminalvoltage of r increases 3% also, and as seen from Fig. 3, the increase ofthe no load current in 1' can by this means'be made to amount to 30%,when the saturation is high enough to make tg a=.01. This enormousgrowth of the current of 1' increases proportionally, the secondaryterminal voltage of k thus securing an efl'ectual decrease in theintensity of the direct current in f with a resultant reduction in theexcitation of the generator G. This enables the voltage of the generatorto be maintained constant within the narrowest limits. In thisarrangement the current transformer is acts directly only on theregulating resistances and therefore the immediate adjustment of theresistance is ob-' tainerl. The rapidity of the regulation isconsiderably increased as compared with existing arrangements. .Ifdesired, the current transformer 70 can be dispensed especially in thecase of low volta nerators.

Having now descrif my invention what I claim as new and desire to secureby Letters Patent is 1. In the regulation of dynamo electric.

machinery, a closed regulating resistance circuit having alternatingcurrent leads connected to equipotential points thereof as regardsdirect current and direct current leads connected to equipotentialpoints thereof as regards alternating current. I

2. In the regulation of dynamo electric alternating current machineryalternating and direct current leads, a closed re ulating resistancecircuit to the equipotential points as regards'alternating current ofwhich the direct current leads are connected and to the equipotentialpoints as regards direct current of which the alternating current leadsare connected; as set forth.

3. In the regulation of dynamo electric alternating current machinery aclosed circuit of regulating resistance, a generator and field coiltherefor, connections for said field coil to said generator and to saidregulating resistance, a source of alternating current and connectionsfrom said source to said resistance; as set forth.

4. In the regulation ofdynamo electric alternating current machinery analternating current generator, an exciter therefor, an exciting coil forthe exciter, a closed resistance circuit, a connection from said exciterto the field coil of the enerator, a connection from said field 001% toan equipotential point as regards alternating current of said resistancecircuit and a connection from said exciter to another equipotentialpoint of the resistance circuit as regards alternating current, togetherwith connections from equi otential points as regards direct current 0said resistance circuit .to a source of alternating current; as setforth.

5. In the regulation of'dynamo electric alternating current machinery analternating current generator, an exciter therefor, an excitingcoil forthe exciter, a closed resistance circuit,a connection from said exciterto the field coil of the generator, :1 connection from said field coilto an equipotential point as regards alternating cur rent of saldresistance circuit and a connecti'on from said exciter to anotherequipotential point of the resistance circuit as regards alternatingcurrent, together with connec-' an exciting coil for the exciter, aclosed resistance circuit, a connection from said exciter to the fieldcoil of the generator, a connection from said field coil to anequipotential point as regards alternating cur-.

ing a current depending on the load of the generator; as set forth.

7 In the regulation of dynamo electric alternatingcurrent machinery analternating current generator, a transformer com prising two coils on acommon core, a connection from the generator to one coil, a connectionfrom thence toanother terminal of the generator, a connection from theother coil to the mains so that the coils are excited by a potential anda load current respectively, together with a transformer,

a closed regulating resistance circuit connected to the secondary ofsaid transformer and an exciter for the generator connected to saidresistance; as set forth.

8. In the regulation of dynamo electricv alternating current machineryan alternating current generator, a transformer comprising two coils ona common core, a connection from the generator to one coil, a connectionfrom thence to another terminal of the enerator, a connection from theother 001% to the main so that the coils are excited by a potential anda load current res ectively, together with a transformer, and a closedregulating resistance .circuit connected to the secondary of saidtransformer with connections from equipotential points as regardsalternating current to the generator field; as set forth.

In testimony whereof, I afiix my signature in presence of two witnesses.

MICHAEL SEIDNER.

Witnesses:

ALEXANDER GARDAGHT, EMIL F IRBINGERT.

